The Tire Pressure Monitoring System (TPMS) is an active safety apparatus for automobiles monitoring pressure of tires in real time to make drivers know about the pressure data at any time and give an alarm timely when the pressure of tires is much lower or larger than the normal pressure. The TPMS has improved the safety in driving a vehicle and effectively reduced traffic accidents, which has social and economical benefits. The function of self-positioning tires in the TPMS means that the position of a tire may be altered when the automobile is in maintenance, a corresponding relationship between an emitter in the tire and the position of the tire shall be set automatically without a manual adjustment.
However, the function of self-positioning tires in the TPMS is not perfect, and achievements in the art for the self-positioning function for tires in the TPMS is listed as follow.
First, a self-positioning method based on field intensity is achieved, in which the cost is low and most functions is achieved via software algorithms. However, in the self-positioning method based on field intensity, wires of a vehicle are needed to depend on, signals are interfaced easily, and the algorithms are complicate and hard to be achieved.
Second, a self-positioning method based on an external encoding memory is achieved, in which signals is not interfaced easily and it has a high successful rate. However, in self-positioning method based on an external encoding memory, an external device is needed in the accessories for tires additionally, which results in high cost, and extra wires are needed, which will probably alter the original wires of the automobile.
Third, a self-positioning method based on a CAN bus is achieved, in which an emitter is needed to be placed near the position of a remote pressure monitoring circuit.